1. Field of the Invention
The present invention relates to an electronic device such as an electronic notebook or a compact electronic calculator which is driven by a battery power supply and uses a pseudo-SRAM, having a self-refreshing function, as a data memory.
2. Description of the Related Art
In a conventional electronic device such as an electronic notebook or a compact electronic calculator driven by a battery power supply, when a DRAM which must be refreshed is used as a memory, refresh pulses must be supplied to the DRAM at a predetermined interval. In addition, even in a device using a pseudo-SRAM having a self-refreshing function, although the self-refreshing function is used in a power-off state, the self-refreshing function is not used in a power-on state because timing control is complicated in a normal operation state. Therefore, in the normal operation state or during use of the device, refresh pulses are always supplied to the DRAM or the pseudo-SRAM at a predetermined interval.
However, in such an electronic device using a battery power supply, as in a case wherein a key input operation or communication is not performed for a long period of time in a normal operation state, even when a CPU is not actually operated, clocks and refresh pulses are kept supplied to the CPU and a memory. For this reason, the power of the battery power supply is wasted.